A direct current to direct current (DC-DC) electrical transformer based on helical electrodes applied to a plasma is described hereinafter. In previously known devices (see, for example, U.S. Patent Application Publication No. 2015/0294842 by Nebel et al.) an input voltage is applied to the helical electrodes and an output is taken from electrodes at opposite the ends of the device. In the presently disclosed device, the secondary current is taken from a split electrode on one end of the device. The present disclosure, in contrast with known apparatuses and methods involving plasma-based transformers, also indicates methods of changing the output voltage and current relative to the input values, and also outlines a method of running the device in reverse in order to convert a stepup DC transformer to a stepdown DC transformer and vice-versa. Thus, this device can work as either a stepup or a stepdown transformer. Although conventional methods can provide long distance DC transmission, such methods are complex and costly. These and other shortcomings are addressed by the present disclosure.